File Processing Concepts and Methods
Explore the concepts of file processing such as access control, order, size, and functions like .eof(), sequential reads, random access, and more. Learn about handling file streams and characters while ensuring correct processing.
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Presentation Transcript
PROCESSING FILES Access order and size Control: eof(), EOF, and operator bool Delroy A. Brinkerhoff
FILE PROCESSING ORDER Sequential Reads or writes data from beginning to end Random / Direct Read or write data in any order Access data by address Keyed / Indexed Requires a key or index file
FILE PROCESSING DATA SIZE Physical access in fixed-sized blocks Operating system hardware storage Logical access in convenient units Characters or bytes Lines Logical blocks
FILE PROCESSING SUMMARY Order Sequential Random Size Character Line Block Buffer Text & Binary Text Binary (infrequently) Text & Binary Binary
THE eof FUNCTION INCORRECT CORRECT ifstream file(file_name); ifstream file(file_name); while (! file.eof()) // 1 { // read file // process data } // initial file read // 1 while (! file.eof()) // 2 { // process data // read file } // 2 // 3 // 3 // 4
SEQUENTIALLY READING CHARACTERS int main() { ifstream in("data.txt"); char c; istream& operator>>(int& c); istream& get(char& c); int get(); in >> c; while (!in.eof()) { cout << '|' << c << '|' << endl; in >> c; } return 0; }
CHARACTER INPUT AND EOF int main() { ifstream in("data.txt"); int c; while ((c = in.get()) != EOF) cout << (char)c << endl; return 0; }
operator bool operator bool int main() { ifstream in("data.txt"); char c; Overloaded casting operator Stream Boolean failbit set if an I/O operation fails while (in.get(c)) cout << '|' << c << '|' << endl; badbit set if a stream is corrupted The conversion operator returns true if either flag is set, false otherwise return 0; } Returns: !(failbit | badbit)
